Photographic half-tone color screen and chart.



` -PATENTBD AUG. 2, 1904.

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A. G. RUSSELL.

API-LICATION FILED APB. 29, 1903.'

PHOTOGRAPHIC HALF TONE COLOR SCREEN AND CHART.

ja/a ven 511.

No. 766,389. PATENTED AUG. 2, 1904. A. G. RUSSELL. PHOTOGRAPHIG HALF TONE COLR SCREEN AND CHART.

APPLICATION FILED APR. 29. 190s. No MODEL. 2 sHBETs-smmz.

fifa* UNITED STATES Patented August 2, 1904.

PATENT OFFICE. y

ARTHUR G. RUSSELL, OF LOS ANGELES, CALIFORNIA.

SPECIFICATION forming part of Letters Patent No. 766,389,

dated August 2, 1904.

.Application filed April 29, 1903. Serial No. 154,801. (No model.)

() ad when@ it nm/y con/cern:

Beit known that I, ARTHUR G. RUssELL, a citizen of the United States, residing at 923 Test Thirty-sixth street, Los Angeles, county of Los Angeles, State of California, have invented certain new and useful Improvements in Photographic Half-Tone Color Screens and Charts, fully described and represented in the following specification and the accompanying drawings, forming a partof the same.

rIhe present invention relates to the making of photographic negatives for the production of photo-engraved plates in the art of threecolor printing. It is common in .preparing the etched plates for such color-printing to first make three negatives of the same object which are caused to differ from one another in making the successive negatives by interposing between the camera and the object socalled ccolor-screens7 of the three primary colorsred, blue, and yellow. The negative taken behind the red screen differs from that taken behind the blue screen or the yellow screen, and the plate pre pared fromsuch anegative when suitably etched is adapted to print with the red ink, while the plates prepared from the other negatives are adapted, respectively, to print with blue and yellow ink, the three 'colors being printed one over the other in a manner well known to produce a coniposite picture in its natural colors of the object photographed.

In the present invention I employ a socalled color chart comprising a tablet bearing spaces of the three primary colors, which tablet is placed in the foreground of the object when photographed with the respective color-screens. The red, blue, and yellow spaces upon the color-chart may be marked I 2 3 or may be arranged in a definite order, as blue and yellow at the ends, with the red in the middle, witha star or other indexmark upon the blue or yellow space, so that the impression upon the negative will always indicate which space upon the chart is the blue.

In the drawings the color-spaces upon the color-chart are shown with the capital letters RB Y applied at the tops of the three spaces to designate the red, blue, and yellowcolor of such spaces. These letters serve as symbols in the impressions made upon the negative to indicate the colors represented thereon. As the disks which carry the color-screens are wholly inclosed .in the casing A, gearing is required to turn the disks,which is provided as follows: Each negative thus exhibits not only the impression of the object, but an impressionof the three primary colors on the color-chart as transmitted by the respective color-screens with which the three negatives are taken, and such impression of the colorchart upon each negative exhibits the separation of the three colors on the several negatives, which separation is so readily distinguished that it indicates at once to any one using the device which color-screen was used in taking each negative, and thus serves as a guide in the succeeding operations with the negatives, resulting positives,or prints which may be produced therefrom in the three-color process of photo-engraving and printing.

The symbols upon the color-chart serve to define the impression of the different colors upon each of the negatives, and in order to secure the impression of the color-chart simultaneously with the impression of the object which is photographed the chart is suitably proportioned to place adjacent to the object, so that it may appear en the margin of the negative in an inconspicuous position.

In the present inventionI provide a rotatable holding-disk in which the color-screens are permanently fixed and mount the same transverse to the lens-tube of the camera and provide it with mechanism for adjusting the screens successively in front of the lens and for locking the disk when thus adjusted. The bolt for effectingsuch locking is preferably a spring-bolt adapted to engage the disk whenever it is turned with one of the screens in the proper adjustment, and the bolt may be so constructed that a key is required to release it, by which means the unauthorized use of the color-screens is prevented.

The invention will be understood by reference to the annexed drawings, in which Figure l is a front view of a camera provided with the color-screen holder, the cover which incloses the holder beingA removed.

IOO

Fig. 2 is a vertical section on the center line of the same. Fig. 3 is a front view of the color-chart; Fig. 4, a cross-section of the same; Fig. an elevation of an object with the color-chart arranged in readiness to photograph for the three required negatives. Fig'. 6 is a view of the negative of such object and chart photographed with the red color-screen, and Figs. 7 and 8 show the negative-photograph with blue and yellow screens.

- In the drawings the camera-chamber and negative are not shown, as their nature is well understood; but the front of the camera is represented in Figs. 1 and 2. with the lens-tube.

o designates the camera-front, the lenstube` and b the lens.

c designates a spindle in the camera-front, with disks CZ attached thereto and formed with three equidistant apertures f'. The glass plates forming the colorscreens g, 7L, and c' are secured between the disks over such apertures, and the spindle c is so situated that the disks may be successively alined with the center of the lens-tube.

As the guide box or casing A is attached to the front @to inclose the disks and has an aperture B in line with the lens-tube for exposing' the negative, a conventional representation of a shutter-fixture C is shown over the aperture L to make such exposure when desired. y l

A hand-wheelj and shaft k arev connected i by gears c with the spindle c for turning the disk to adjust the color screens. Holes Z are formed in the disk, and a spring-bolt m is fitted to the front a and adapted to slip into such holes when each of the screens is successively alined with the lens. A hand-wheel a and shaft o are connected by a crank p with a rod p', attached to the bolt m., to retract the same from the disk when it is desired to adjust the disk. A hole q is shown in the bolt m where it projects through the casing or box A, and a padlock fr is shown applied to such hole to prevent the retraction of the bolt until the padlock is removed. The use of a padlock with a key to open the same thus serves to secure the disk from unauthorized rotation, and any other form of lock-bolt would obviously be an equivalent.

Color-dimi.-The color-chart may consist of any tablet bearing spaces properly tinted with the three primary colors and the several colorspaces marked, respectively, with dierent symbols, which appear in connection with the impression of such colors upon the negative when taken. In Fig. 3 of the drawings the chart is shown formed with a back piece s, paper z?, bearing the colors, and a glass cover t, the glass cover protecting' the colored spaces from injury by soiling or abrasion. The margin of the glass cover is shown provided over the red space with the letter R at the left end of the chart, over the blue space in the middle of the chart with the letter B, and over the yellow space at the right-hand end of the chart with the letter Y, these letters forming the symbols to desig'- nate the respective impressions which these spaces make upon the negative, as shown in Figs. 5 to 8, inclusive. In Fig'. 5 the object is represented as a circle with five bands of color extended across the same and shaded in a conventional manner to represent red where a letter `r is applied, blue where the letter Z) is applied, yellow where the letter g/ is applied, green where the letter g is applied, and orange where the letterois applied. The screen in Fig. 3 is also shaded-conventionally in three places, (lettered, respectively, r, b, and and such screen is shown upon a smaller scale below the object inFig. 5. Fig'. 6shows the appearance of the negative when the object and color-chart are photographed through the red screen, the red and yellow appearing' as black and the` blue appearing' as white and the green and orange appearing as gray or semitransparent upon the negative. Fig. 7 shows the appearance of the negative with the object and color chart photographed through the yellow screen, and Fig. 8 the negative with the object and chart photographed through the blue screen. These negatives show similarly variations in the bands upon the photograph of the object, and the colorchart in each of the negatives shows variations produced by the several screens.

The color-chart on the negative in Fig. 6

Ashows the blue portion of the chart white and the red and yellow portions black.

rlhe color-chart on the negative in Fig. 7 shows the red portion of the chart white and the blue and yellow portions black.

The color-chart on the negative in Fig. 8 shows the yellow portion of the chart white and the red and blue portions black.

r 1he letters R, B, and Y, which appear upon the chart in Fig. 3, also appear upon the negatives, so that the operator can instantly tell by the color-chart upon the negative which screen has been used in taking such negative. such negatives, the representation of the colorchart is of course reversed, but the letters remain, and the operator can thus tell through which screen the original negative was taken from which the positive is produced.

Operation. 0f Hw Clcfvz'ceafThe operation of making the three-color negatives by my invention is as follows: The color-chart is arranged, as shown in Fig. 5, in the foreground of the object to be photographed, and one of the negatives is inserted in the camera and the object focused. The spring-bolt is then retracted by the hand-wheel n, and the disk (Z, 4by means of the hand-wheel j, is partially rotated and the hand-wheel a released to let the bolt press upon the disk. any one of the color-screens is turned in line with the lens, the spring-bolt enters the hole TOO Vhen the positives are made from l/Vhen in the disk and arrests the same and holds the color-screen in such position. The negative is then taken through such color-screen and a fresh plate inserted in the camera, the disk shifted to bring the next screen in line with the lens, and another neg'ative is taken through the succeeding' colorscreen, and, finally, a third negative is taken throug'h the third color-screen. The impression of the color-chart is different upon each of the neg'atives and ors in such a manner that the negatives can be readily distinguished from one another without any other mark applied to the negative. IVhen the positives are made and also the prints from the negatives, the impression of the color-chart still persists and operates as a g'uide in each step of the process.

In working the three-color process t-hehalftone negatives exhibit the same variations as the original negatives and the etched plates are the same as the positive, thereby making' the colors print solid. The impression of the color-chart upon the etched plates would be cut offA when finished; but the picture printed by each of the plates would still correspond mathematically with the separation of color exhibited upon the chart and negatives.

The use of the color-chart is thus of great value to the operator in making' and handling' the negatives and positives in three-color photography, and the use of the apparatus also greatly facilitates the taking of negatives by the three-color process.

Having thus set forth the nature of the invention, what is claimed herein is` l. The apparatus for conjoint use in photographing' three-color negatives, comprising' a camera, a set of three "color-screens and a three-color chart of suitable size to photograph with the object, such chart having spaces of the three primary colors marked with different symbols adapted to indicate the colors symbolically in the negative taken from such color-chart and obj ect,the wholearranged and operated substantially as herein set forth.

2. A color-chart for use with,color-screens in making negatives for three-color printing, comprising color-spaces corresponding' with the colors of the color-screens, which spaces have different symbols to indicate the colors symbolically in the negatives taken from such colorchart.

3. In an apparatus for making three-color negatives, the combination, with the camerafront and the lens-tube fixed therein, of the spindle c having the disk Z parallel with the front and carrying' the three color-screens, the box or casing A wholly inelosing the disk and color-screens, and provided with the usual apshows the separation of the col-A a suitable tablet bearing three erture and shutter, and the hand-wheel,y'with gearing connecting' the same to the spindle c for turning' the disk to adjust the "colorscreens.

et. In an apparatus for making' three-color negatives, the combination, with the camera lens and tube, of a rotatable disk carrying the three color-screens 77'transverse to the lenstube, means for rotating the holder to bring' the color-screens successively in line with the lens-tube, and means for locking the disk when thus adjusted.

5. In an apparatus for making' three-color negatives, the combination, with the camera lens and tube, of a rotatable disk carrying the three color-screens transverse to the lenstube, a spring-bolt set transversely to the 1'0- tatable holder, the holder being' provided with holes to engage such bolt when the screens are alined with the lens-tube, and means for withdrawing' the bolt from the holes and turning' the disk to adjust the screens.

6. In an apparatus for making' three-color negatives, the combination, with the camerafront and the lens-tube fixed therein, of the spindle c having` the disk (Z parallel with the front and carrying' the three colorscreens, the box A inclosing' the disk and provided with the usual aperture aud shutter, a lock-bolt fitted to the "front to engage the disk, and handpieces adapted to rotate the disk-spindle and to operate the lock, substantially as herein set forth.

7. In an apparatus for making' three-color negatives, the combination, with the camera lens and tube, ofl a rotatable disk carrying the three color-screens7 transverse to the lenstube, means for rotating the holderto bring' the y"color-screens successively in line with the lens-tube, a bolt for securing' the disk when adjusted, and a lock provided with a key and arranged and operated to fasten the bolt to prevent the turning of the disk.

8. In an apparatus for making tln'ee-color negatives, the combination,with the camerafront7and the lens-tube fixed therein, of the disk carryingl the -color-screens transverse to the lens-tube, a spring-bolt arranged and operated to eng'ag'e the disk automatically when each of the screens is in line with the lens-tube, and means provided with a key for releasing' such spring-bolt to permit the turning' of the disk.

ln testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

ARTHUR G. RUSSELL. Witnesses:

FLORENCE MAYBELLE Case, FLORA C. RAYMoRe.

TOO 

